What is Treatment-Induced Metastasis?

Treatment-Induced Metastasis (TIM) is the term given to the paradox in oncology in which an anticancer treatment first casues a tumor to shrink, followed by the rapid growth (metastatic spread) of that tumor.

It’s not a term anyone wants to hear, nor a phenomenon anyone wants to believe even exists.

According to a new article in Cancer Research by John M.L. Ebos, TIM can be caused by known therapies including surgery, chemotherapy, radiation and targeted therapy:

Under certain conditions, nearly all cancer treatments can facilitate metastatic spread, often in parallel (and sometimes in clear contrast) with tumor reducing benefits.

Put another way, TIM is when the treatment they give you to fight your cancer winds up either promoting the growth of the cancer or allowing it to build a resistance to treatment, which ultimately leads to the same thing- tumor growth.

The concern, writes Jim Daley of Cancer Therapy Advisor is that therapy causes a change in the tumor microenvironment that leads to the promotion of metastasis.

One reason this has not fully been embraced as a clinical reality is that it is backed up by decades of preclinical research—-meaning decades of dealing with mice in the laboratory, and actual clinical research—-in people—-into the phenomenon is scant, beyond observation.

The good news—if there can be any good news here—is that the problem appears to be more closely associated with targeted therapies, such as those that work to block certain cell signaling pathways. That would include the many vascular endothelial growth factor receptor inhibitors (VEGF) approved by the FDA since 2004. With the exception of Iclusig (used to treat chronic myeloid leukemia) these drugs are rarely used in the treatment of lymphoma—in fact most are indicated for either thyroid cancer or kidney cancers. Another minor exception might be Avastin (bevacizumab), which likely has been used more against lymphoma in unimpressive clinical trials sponsored by the drugmaker than in actual practice.

Prodding the Beast: Assessing the impact of treatment-induced metastasis.
"Can Cancer Treatment Be Causing Cancer Spread?"